Search

Stacked Bi2Sr2Ca2Cu3O10/Ag tapes were examined for alternating current losses.

Application of positron annihilation spectroscopy (PAS) enables complete analysis and determination of the distribution, level and nature of defects in SiO2-Si- and Si-based structures. PAS reveals the changes in interface trap density, hydrogen detrapping from SiO2-Si interfaces and radiation disruption in the SiO2-Si structures. The applicability of PAS to analyze compound semiconductor systems helps probe and enhance its future applications.

Pr-Fe-B die-upset magnets exhibited a lower remanence and a higher coercivity than analogous Nd-Fe-B magnets, with the microstructure of both magnets exhibiting similarities. Enhanced magnetic domain wall pinning and increased coercivity in Pr-Fe-B magnets was due to the thick intergranular phase. Hot-worked Pr2Fe14B magnets were obtained from melt-spun ribbons.

Depth profiling and data analysis in slow position experiments reveal more information on the position implantation. The simulation of the behavior incident at different kilo electron volt energies are effected by the Monte Carlo simulations. The mechanisms of conduction- electron and longitudinal acoustic phonon scattering describe the final stages of position thermalization in Al, Cu and Au from 25 electron volts. The data, including implantation profiles, fraction and energy distribution of reemitted positron, are yielded by the Monte Carlo simulation.

Electron microscopic and magnetization analyses of two die-upset rare-earth magnets with bulk contents of Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6 at high temperatures reveal that nucleation of reversed regions in the iron-rich intergranular sites of reduced anisotropy serves as the primary reversal process in these magnets. Nucleation of reverse domains promotes the coercivity of the magnets. High coercivity can be achieved by grouping nonmagnetic atoms to the grain-boundary phase.

The alteration of initial susceptibility and metamagnetic transition field of the giant magnetocaloric material Gd5(Ge,Si)4 by 100 nm coatings of Fe and Al is discussed. The effect of the magnetic field in the metamagentic phase transition range is enhanced by the strain conferred by 100 nm coatings.

Recoil curves from the major hysteresis loop are measured on a sample of PrFeB as a function of temperature from 150 to 300K in order to understand the effects of nucleation fields and intergranular dipolar interactions on the magnetization reversal mechanism. The result is consistent with the hypothesis that at a high temperature the nucleation field for the creation of new domain walls is lower than the dipolar field, which stabilizes residual areas of reverse magnetization.

Investigates factors affecting coercivity in Nd-Fe-B alloys. Reversal mechanisms; Temperature dependence; Estimation of constituent grain size by diffraction methods; Isothermal remanence magnetization; Measurement of dc magnetization.

Examines hard nanocomposite alloys affected by anomalous high-temperature coercivities. Measurement of remanence bromine (Br) and coercivity hydrogen (H) ci on a series of four meltspun remanence enhanced nanocomposite alloys; Characterization of the phase constitution and microstructural sale of the alloys.

Presents an abstract of a theoretical analysis of chemical bonding and solute systematics in compounds of rare earth metals and transition metals. Description of a second-moment-approximation-based many-atom bonding theory; Use of theory for describing the systematics of energies and volumes of formation.